Post by thread:[OT]: Hard Drive Crash Recovery. Crowbars

The 'pro' supplies used in high end boxes have serious 'crowbar' SCRs on their outputs to prevent this sort of thing from happening. When you have $10k of high performance server/hard drives, you don't worry about $10 of fail-safe parts. I suppose you could make up a poor-man's-crowbar with some high wattage zeners rated at a half volt about the supply values (notably the 5V and 12V rails). If the supply goes berserk, the zeners clamp and blow the primary fuse. Wire it up to an old hard drive connector (or Y cable) for easy installation. Now that you've made me think about it, I'll be doing this tomorrow. I once has a power supply where the 5V & 12V leads for a drive were reversed. Brand new SCSI HD and the 'magic smoke' came out the first time I powered it up. The dealer refused to replace the fried drive since "you should have checked that the connectors were OK". I certainly check now. I also highly UNrecommend them to anyone who asks. In the end they lost a lot more that the replacement cost of the drive. A relatively cheap and quick way to do backups is to purchase a second BIG hard drive in removable drive bay. It is used ONLY for backups. You pull it out of the system and take it off site once you've done the backup. With two drives it's even more reliable. You take one home with you, and bring the alternate in to work the next day (or week). Robert Bob Blick wrote: {Quote hidden}> > > I like mirrored drives a heck of a lot better. I've had tape media problems > > as well as other (ahem, "operator headspace") issues. I also never need to > > remember to swap out a mirror drive... but I could if I needed off-site > > backup storage. > > Off-site's not a bad idea. This all hits very close to home. The power > supply in my office computer decided to go ballistic and uncontrolled last > week. The fans sounded like jet engines, and almost masked the popping > sounds of chips losing their epoxy. Smoke poured out, the power switch(ATX > soft power, ya know) did nothing. > > Everything was toast. The hard drive would not spin. I got an identical > new drive and swapped boards, now it spun up fine, but just went > clack-clack. I guess the internal head electronics was toast. Estimate > from Drivesavers for their "economy" service was $1900 to recover the > data. Luckily I was well backed up. > > Except now I have to make friends with a new computer. > > Networked backups a good idea, off-site backups even better! I've never > heard of this happening before, but I'm paranoid now. > > Cheers, > > Bob -- http://www.piclist.com hint: To leave the PICList spam_OUTpiclist-unsubscribe-requestTakeThisOuTmitvma.mit.edu

On 25 Feb 2002 at 19:14, Robert Rolf wrote: > The 'pro' supplies used in high end boxes have serious 'crowbar' SCRs on > their outputs to prevent this sort of thing from happening. When you have $10k > of high performance server/hard drives, you don't worry about $10 of fail-safe > parts. I've never seen a supply with multiple crowbars. Usually(like this one) there is a crowbar on the 5v supply, plus a 339 quad comparator sensing all supplies. The 5 volt line never got too high, it was the other supplies that did all the damage. That's why the video card, ethernet card, and floppy drive survived. Everything else was toast. Computer was plugged into a UPS, it wasn't a surge, the power supply just picked a good time to go full duty cycle. Or perhaps the crowbar somehow triggered, and it forced everything else up as it tried to restore +5 to the proper voltage? Redarding expensive power supplies, I'm not convinced they are any more reliable. When I bought a system with an Athlon, I followed the recommendation and bought the best power supply I could, and went so far as to buy ones on the list at AMD. Three power supplies from two different brands all failed for various reasons within a few months. I now have a piece of crap power supply in it and it's been working three years. The expensive power supplies were heavy, had lots of nice parts in them, but they were less reliable. Cheers, Bob -- http://www.piclist.com hint: To leave the PICList .....piclist-unsubscribe-requestKILLspam@spam@mitvma.mit.edu

Bob Blick wrote: > On 25 Feb 2002 at 19:14, Robert Rolf wrote: > > > The 'pro' supplies used in high end boxes have serious 'crowbar' SCRs on > > their outputs to prevent this sort of thing from happening. When you have $10k > > of high performance server/hard drives, you don't worry about $10 of fail-safe > > parts. > > I've never seen a supply with multiple crowbars. Usually(like this The Compaq's I once attempted to service did have multiple crowbars, as did the DEC PDP 11/xx supplies. Had lots of PDP supplies try to go AWOL, but the crowbars did their job. > one) there is a crowbar on the 5v supply, plus a 339 quad > comparator sensing all supplies. The 5 volt line never got too high, it If designed correctly, the 339 would have triggered the 5V crowbar and killed the supply with high loading. Of course a few milliseconds of 50V isn't going to sit well with 12V parts. > was the other supplies that did all the damage. That's why the video > card, ethernet card, and floppy drive survived. Everything else was > toast. > > Computer was plugged into a UPS, it wasn't a surge, the power > supply just picked a good time to go full duty cycle. Or perhaps the > crowbar somehow triggered, and it forced everything else up as it > tried to restore +5 to the proper voltage? Yes, a lot of supplies use the 5V as a reference for everything else. Pull it low, but not dead, and it's quite possible the other voltages would go high enough to pop something. The original IBM PC AT supply had a low ohm, high watt resistor to load the 12V supply if you didn't have a hard drive. With the ballast resistor disconnected you got 12V, and 3V on the 5V line. Brilliant design, NOT! What does a high power zener cost these days? Why can't the manufactures charge an extra $5.00 to have a bit of 'robustness' in a design? > Redarding expensive power supplies, I'm not convinced they are > any more reliable. When I bought a system with an Athlon, I Brand name? With a long warrantee that they'd have to 'make good' on if their supply failed? Tell us what we should avoid in future. > followed the recommendation and bought the best power supply I > could, and went so far as to buy ones on the list at AMD. Three > power supplies from two different brands all failed for various > reasons within a few months. I now have a piece of crap power > supply in it and it's been working three years. The expensive power Check that the fans are still spinning. Every cheap supply we've had has lost it's fans after 3-5 years. Of course our machines are on 7x24 since reboots take too darned long. > supplies were heavy, had lots of nice parts in them, but they were > less reliable. That is unfortunate. All it takes is ONE weak component if the design has intrinsic flaws. Robert -- http://www.piclist.com hint: To leave the PICList piclist-unsubscribe-requestKILLspammitvma.mit.edu

> What does a high power zener cost these days? > Why can't the manufactures charge an extra $5.00 to have a bit > of 'robustness' in a design? You *are* talking about PC power supplies, correct? This would be a 50% price increase in the cost of the supply. Take a look at these things some time, most (all?) are not even UL listed, as that would add to the cost too much. I can get a new 300watt supply for as low as US$12.00. I wouldn't use it in my computer, I'm just saying. I have seen a good many supplies go bad, but I have never seen one damage the computer......yet. Most failures seem to be due to the fan stopping. It's only a matter of time after that. ;-) I've sure seen some melted parts as they will get a tad warm inside with no fan running. michael brown -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

With all these worries about hard-disk crashing, has anybody consider or even purchase RAID controllers as an insurance. See link http://www.promise.com I have no idea about this product...been reading something about RAID...which stands for "Redundant Array of Indepedent(Inexpensive) Disks" If what they are selling is what I think it is, then you insert this card into your PC with a number of hard disks, example 4 hard-disk. If one hard-disk crashes, then information from the other 3 hard-disk can be used to regenerate the lost data. It is also suppose to make the 4 disk look like one large disk (maybe like total of 3 disks capacity) It is also suppose to be faster, as data are stored across multiple disk, and retrival is faster because 3 disks are spinning to get data simultaneously.. I thought such things are availiable only for HIGH END COMPUTERS, and I am surprise it is avaliable for PC. Anybody tried this product before ? and Did I understand what RAID is correctly ? Derek -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

On Wed, 27 Feb 2002, Derek Chan wrote: > If what they are selling is what I think it is, then you insert this card > into your PC with a number of hard disks, example 4 hard-disk. If one > hard-disk crashes, then information from the other 3 hard-disk can be used > to regenerate the lost data. Correct, assuming RAID 5. RAID 0 - Striping. Makes 2 or more disks look like one big drive, no redundancy. RAID 1 - Mirroring. Keeps two copies of the disk on 2 spindles. Full reundancy. RAID 3 & 4 - Forget the details, but they're not commonly used. RAID 5 - Striping with parity. A spare spindle is used for parity information so you can lose one disk (and only one) without losing data. Requires 3 or more disks. Then there are combinations - RAID 15 is mirrored RAID 5 sets, etc. for the truly critical apps & data. I use RAID 1 mirroring in my Linux machine now. No special controller required, the drivers are bult into the OS. Solaris and most other UNIX flavors have this as well. > I thought such things are availiable only for HIGH END COMPUTERS, and I am > surprise it is avaliable for PC. Anybody tried this product before ? and Did > I understand what RAID is correctly ? Yep, you did. I don't use the Promise controller, but a friend does and likes it. Actually he bought the ATA-100 controller and found out there's one jumper to make it a RAID controller also, same hardware just a jumper-seleted software feature that saved him some money. He's tested it (as I tested my software RAID); works perfectly. Since they're IDE drives there's no hot swap capability, but it's not a critical business server, so no big deal. I do high end computers for a living - UNIX front end systems manager for a large online brokerage. In a critical application we use either mirroring or RAID 5 - depending on the space needed - then deploy two or more identical, load balanced servers so if one fails we're still OK. Of course there is always the EMC disk arrays... multiple TB of RAID5 space that can be dynamically allocated. Every house should have one! 8-) Dale -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

I use the Promise Fasttrack 66 RAID cards in small stores. I have two drives set up in each server as a mirrored configuration, and each night the server backs up the data to a seperate computer on site. This gives 2.5 points of failure - if a single HD fails the server keeps chugging along without a single complaint. I have to down the server to replace the bad HD (It supports hot swap, but does not support dynamic rebuilding - meaning it won't re-mirror a drive while it's in use). If the server crashed so hard both hard drives are toast then I have the other on site backup. The event that all three hard drives are destroyed at the same time without the store being destroyed as well are so remote as to not be worried about. We don't care much about the data if the store is completely gone (fire, acts of nature, etc), so an off site backup tips the cost/return on investment scale. I used one in my personal machine for awhile in a striped configuration (block one on the first drive, block two on the second, block three on the first, etc) with two 7200rpm 20GB hard drives, and it performed noticibly better than another machine with a faster processor that was using two 10,000rpm scsi hard drives. They are not considered 'professional', though, and I wouldn't depend on them completely - ie, keep another reliable backup. I've never had a problem with them though, and they've been in place in over 12 stores for nearly a year now - pretty severe use. -Adam Derek Chan wrote: {Quote hidden}>With all these worries about hard-disk crashing, has anybody consider or >even purchase RAID controllers as an insurance. See link >http://www.promise.com > >I have no idea about this product...been reading something about >RAID...which stands for "Redundant Array of Indepedent(Inexpensive) Disks" > >If what they are selling is what I think it is, then you insert this card >into your PC with a number of hard disks, example 4 hard-disk. If one >hard-disk crashes, then information from the other 3 hard-disk can be used >to regenerate the lost data. > >It is also suppose to make the 4 disk look like one large disk (maybe like >total of 3 disks capacity) > >It is also suppose to be faster, as data are stored across multiple disk, >and retrival is faster because 3 disks are spinning to get data >simultaneously.. > >I thought such things are availiable only for HIGH END COMPUTERS, and I am >surprise it is avaliable for PC. Anybody tried this product before ? and Did >I understand what RAID is correctly ? > >Derek > >-- >http://www.piclist.com hint: PICList Posts must start with ONE topic: >[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads > > > > > -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

Something I've not seen discussed on this thread (yet) to consider: Most data loss is the result of intentional user initiated actions. While the data loss is not necessarily intentional, I know so many people who were just "cleaning up their C: drive" and ended up wiping out entire subdirectories (including the O/S many times) and were left with nothing. Even a six figure EMC disk array doesn't protect against that ... there is simply no substitute for permanent (or at least semi-permanent) backups which are separate from the live data. Even having a second hard drive that you synchronize with nightly leaves this area exposed ... ex: user deletes file, synchronization process runs nightly for 3-4 days (deleting file from synchronized media), finally user realizes they deleted file and want it back. Seen it too many times. -- Mitch -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

I have actually been considering to run down to the computer to purchase the Promise Card and plug it into my PC. Beside "promise" any other company making this stuff or any recommendation ? It sure beat having to make a backup copy once a while wondering when the disk will fail, because all I need to do it replace the faulty disk, at I am up and running again without data loss. Derek -----Original Message----- From: pic microcontroller discussion list [.....PICLISTKILLspam.....MITVMA.MIT.EDU]On Behalf Of M. Adam Davis Sent: Wednesday, February 27, 2002 10:23 AM To: EraseMEPICLISTspam_OUTTakeThisOuTMITVMA.MIT.EDU Subject: Re: [OT]: Hard Drive Crash Recovery. Crowbars I use the Promise Fasttrack 66 RAID cards in small stores. -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

> I have actually been considering to run down to the computer to > purchase the Promise Card and plug it into my PC. Beside "promise" > any other company making this stuff or any recommendation ? Adaptec. IDE versions ATA1200A and ATA2400A (if I recall correctly). SCSI versions too. Mylex ExtremeRAID or DAC960 (older models). I've only used their products on SCSI drives. AMD(?) MegaRAID; SCSI. Dell's PERC SCSI RAID (probably a rebrand). > It sure beat having to make a backup copy once a while wondering > when the disk will fail, because all I need to do it replace the > faulty disk, at I am up and running again without data loss. RAID is not the same as off-site backups. It boosts performance or protects against failure of a single hard disk or both. To be able to hot swap drives and rebuild on the fly requires a drive enclosure/chassis and carriers that support such activities. It is frequently easier to buy it built into a server, such as Dell's Poweredge 1500SC, 2500, etc. If you want hot swap drive capability in an external enclosure, check out Dell, Compaq, IBM, and other. One third party that makes a nice (though expensive) external enclosure with redundant power supplies and hot swap is Kingston's Data Silo products. Lee Jones -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

On Wed, 27 Feb 2002, Derek Chan wrote: > I have actually been considering to run down to the computer to purchase the > Promise Card and plug it into my PC. Beside "promise" any other company > making this stuff or any recommendation ? Yeah, 3ware makes some pretty cool stuff. 8 IDE drives in a single PC on a controller acting as a non-blocking switch. Allows up to 8 drives to be concurrently performing ATA requests much the way SCSI works. Pricey, but nice!! -- Mitch -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

>> I have actually been considering to run down to the computer to >> purchase the Promise Card and plug it into my PC. Beside "promise" >> any other company making this stuff or any recommendation ? >Adaptec. IDE versions ATA1200A and ATA2400A (if I recall correctly). >SCSI versions too. I do not know if DPT make ATA versions, but their SCSI cards used to do nice RAID arrays invisible to the op system. Also be aware that win NT/2k/XP all have raid built into them. Unfortunately the workstation/pro version does not do mirror drives but allows striping which always seemed a backwards way of looking at it. The server versions allow all useful RAID modes. -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

The Tayan motherboard in the machine I'm running on http://www.hallikainen.org has a Promise RAID controller on the motherboard. It supports four drives and two modes. I don't remember the mode numbers, but they allow for drive mirroring or drive striping. Mirroring gives redundancy by always writing stuff out to two drives. Striping spreads the data across multiple drives. I believe there is a striping method that allows recovery on loss of a drive, but this does not support it. Nonetheless, I am running striping to make it fast and get a lot of capacity (120 GB on four drives). The controller shows up as a single SCSI drive to the operating system. Promise has a driver for RH 7.1 Linux that I'm using. The machine boots from this. They say they are working on a driver for RH 7.2 Harold FCC Rules Online at http://hallikainen.com/FccRules Lighting control for theatre and television at http://www.dovesystems.com ________________________________________________________________ GET INTERNET ACCESS FROM JUNO! Juno offers FREE or PREMIUM Internet access for less! Join Juno today! For your FREE software, visit: dl.http://www.juno.com/get/web/. -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics